Scientists Grapple With Question of COVID-19 Vaccine Booster, as Some Countries Push Ahead COVID-19 Science 30/07/2021 • Svĕt Lustig Vijay Share this:Click to share on Twitter (Opens in new window)Click to share on LinkedIn (Opens in new window)Click to share on Facebook (Opens in new window)Click to print (Opens in new window) Healthcare professional administering a COVID-19 vaccine at Yankee Stadium in the Bronx, New York in February. This article is the first in a series on COVID-19 booster vaccines, which is an evolving discussion as more evidence emerges about the performance of vaccines against variants. A vigorous debate is underway in the global health community over the potential benefits of COVID booster vaccines for healthy people who have already received a full course of a WHO-approved vaccine, with Pfizer pushing hard for boosters to address variants. Israel announced on Wednesday that it would administer boosters for people over the age of 60 starting next week, joining Hungary, Turkey, Thailand, Bahrain and the United Arab Emirates – although the US is holding back for now. Vaccines are still a scarce resource and giving third doses to people in wealthy countries means diverting doses from vulnerable people in poor countries, the WHO has warned. Some critics have added that the move is unethical and that it opens the door to the development and global circulation of new variants. But the pharmaceutical industry, and other booster shot proponents have argued that boosters could be needed in the future, citing lab-based data showing that antibody responses wane six months after the second jab, but rise again following a third jab. Booster shot proponents, including a number of leading scientists in Israel, which is now seeing a surge in COVID cases, have also cited new data suggesting that vaccine protection may be waning among older people whose immune systems are weaker – along with being less effective in protecting people against the Delta variant. To address the Delta variant, both Pfizer and Moderna aim to develop new formulations of their vaccines to target more of the SARS-CoV2 spike protein, with plans to roll those new vaccines out by the end of the year. But a debate is also raging over whether boosters of the existing vaccine are needed even before that among certain groups of people. Too early to tell? IFPMA Director-General Thomas Cueni “Manufacturers and developers are studying the need for boosters based on whether there is waning immunity over time and cross-protection against variant strains,” Thomas Cueni, the head of the International Federation of Pharmaceutical Manufacturers (IFPMA), told Health Policy Watch. “Based on these learnings, companies are also advancing studies of both boosters and new formulations to address SARS-CoV2 variants emerging across the globe. “If data from studies demonstrate, when available, that there is a need for a booster dose of a vaccine, or a new variant-specific vaccine, we will share the necessary information and work with governments on new agreements or updates to existing agreements to supply booster doses or variant-specific vaccines, subject to regulatory authorization,” he added. However, booster skeptics have charged that lab-based metrics like antibody responses to vaccines are not a watertight proxy for the real-life performance of vaccines or for immunity against SARS-CoV-2. They have argued that it is too early to tell whether booster shots are needed in the general population. Still, there appears to be consensus that booster jabs could save lives and precious hospital capacity if they were prioritized in immuno-compromised patients, who are roughly twice as likely to die from COVID-19 as healthy people and often display woefully inadequate antibody responses, even after receiving two vaccine jabs [see related story]. Going forward, policymakers will have to re-evaluate whether vaccine policies should aim to prevent infection and symptomatic disease, or whether it is more realistic to prevent severe disease and death – in light of gaping vaccine shortages and the rapid spread of new variants like Delta, public health experts told Health Policy Watch. Dr Michael Osterholm, Director of the Center for Infectious Disease Research and Policy (CIDRAP) at the University of Minnesota, said that there are still too many unknowns. “What we’re really looking for are these larger studies but that takes time. What’s important is what happens in the next six months or the next year,” he told Health Policy Watch in an interview. “Do [fully vaccinated people] get infected or not? Do they have waning immunity? The pandemic has only been around for 1000 days. We just don’t know yet.” US health protection agency says boosters not needed for now After a private meeting between Pfizer and US regulators about a third booster jab earlier this month, the US Centres for Disease Control (CDC) and the US Food and Drug Administration (FDA) responded that “Americans who have been fully vaccinated do not need a booster shot at this time”. “We are prepared for booster doses if and when the science demonstrates that they are needed….People who are fully vaccinated are protected from severe disease and death, including from the variants currently circulating in the country such as Delta,” said a joint statement from CDC and FDA in early July. “People who are not vaccinated remain at risk. Virtually all COVID-19 hospitalizations and deaths are among those who are unvaccinated.” But this week, a leaked CDC report revealed that a person infected with the Delta variant may infect five to nine others on average – making it at least twice as contagious as the original SARS-Co-v2 lineage and as infectious as chicken pox. In addition, the report found that vaccinated people may be as likely to spread the virus as unvaccinated people. Those findings, first reported by the Washington Post, are thought to have pushed the CDC to reverse its mask mandate to recommend that everyone – including those fully vaccinated – wear masks in certain settings in public indoor events. New @CDCMMWR finds Delta variant causes vaccine breakthrough infections. Jurisdictions might consider expanded prevention strategies, including masking in indoor public areas, particularly for large public gatherings that include travelers from many areas. https://t.co/Q8d9kmQ4Mj pic.twitter.com/aTR6bKTwER — CDC (@CDCgov) July 30, 2021 Thailand, UAE and Bahrain are already giving boosters Meanwhile, Thailand, United Arab Emirates (UAE) and Bahrain have pushed ahead with a booster jab in healthy people who have received both shots of Sinopharm, Sinovac, and AstraZeneca vaccines – all viewed as less efficacious than the mRNA vaccines produced by Pfizer and Moderna. Soon, other large G-7 nations like the United Kingdom, the United States, and Germany, may also follow suit following fresh concerns that two vaccine shots, even of the most effective vaccines, may not be sufficient to prevent SARS-CoV-2 infection and mild disease against highly contagious variants like Delta. Yet large-scale data from the UK, Qatar, and Israel, demonstrates that vaccines confer robust protection against hospitalization and death from SARS-CoV-2 – and that those trends persist against variants like Delta. In addition, a multi-country study supported by Pfizer involving almost 45,000 people revealed that, with the Beta variant, vaccine efficacy against infection drops from 96% to 84% after six months. The study, which is not yet peer-reviewed, also stressed that efficacy against hospitalisation stands at 97% after six months. Those findings, researchers said, demonstrate that the Pfizer vaccine “prevents COVID-19 effectively” six months after the second jab: “The data in this report demonstrate that BNT162b2 [Pfizer] prevents COVID-19 effectively for up to six months post-dose two across diverse populations, despite the emergence of SARS-CoV-2 variants, including the B.1.351 [Beta] lineage, and the vaccine continues to show a favourable safety profile,” concluded the study. It adds that “ongoing follow-up is needed to understand the persistence of the vaccine effect over time, the need for booster dosing, and timing of such a dose….booster trials to evaluate safety and immunogenicity of BNT162b2 are underway to prepare for this possibility.” These findings come on the heels of an earlier study in some 40,000 people in the UK, published in the New England Journal of Medicine (NEJM), which, similarly to the Pfizer study, found that two shots of Pfizer still confer strong protection against symptomatic disease, with a protection of 88% against the Delta variant, in comparison to 94% against Alpha, the variant first discovered in the UK. The NEJM study indicates that fully vaccinated people are likely to be well protected against variants like Delta, if they receive both shots, concluded the authors of the study. “Overall, we found high levels of vaccine effectiveness against symptomatic disease with the delta variant after the receipt of two doses,” the authors said. “These estimates were only modestly lower than the estimate of vaccine effectiveness against the alpha variant,” they added, noting that similar trends were seen with the AstraZeneca vaccine. However, they warned that a single dose of the Pfizer/BioNTech vaccine conferred substantially less protection against Delta compared to Alpha – with a drop in effectiveness from 50% to 31% for symptomatic disease, respectively. In US, 97% of people hospitalized for COVID-19 are unvaccinated In the US, too, it appears that fully vaccinated people develop mild but not severe disease or death. Rochelle Walensky, the Director of the US Centers for Disease Control (CDC), has said that 97% of hospitalised COVID-19 patients in the US are unvaccinated – suggesting that achieving high vaccination coverage can effectively curb transmission, hospitalisation and deaths from COVID for now. “We are seeing outbreaks of cases in parts of the country that have low vaccination coverage because unvaccinated people are at risk,” said Walensky. And communities that are fully vaccinated are generally faring well. “The good news is that if you are fully vaccinated, you are protected against severe COVID, hospitalisation, and death, and are even protected against the known variants — including the Delta variant — circulating in the country,” Walensky. “If you are not vaccinated, you remain at risk. And our biggest concern is that we are going to continue to see preventable cases, hospitalisations, and, sadly, deaths among the unvaccinated.” High-risk groups in poorer countries should be vaccinated first The WHO, meanwhile, has taken a strong stance against boosters in healthy people who are fully vaccinated, asserting that scarce vaccine doses need to be directed first of all to countries and populations where health workers and older people haven’t yet been vaccinated at all. “Some countries and regions are actually ordering millions of booster doses before other countries have had supplies to vaccinate their health workers, and the most vulnerable. I ask you, who would put firefighters on the front line without protection – and who are most vulnerable to the flames of this pandemic? Health workers are on the front lines,” the WHO head Dr Tedros Adhanom Ghebreyesus said earlier this month. “Currently, data shows us that vaccination offers long lasting immunity against severe and deadly COVID-19. The priority now must be to vaccinate those who have received no doses and protection,” the WHO DG added. In light of the gaping shortage of vaccines in low- and middle-income countries, as well as the scarcity of data about the benefits of boosters in healthy people, prioritizing vulnerable populations appears to be a viable policy option, at least for now, experts told Health Policy Watch. “There isn’t much evidence regarding the third shot in healthy people who are fully vaccinated,” Antoine Flahault, the Director of Geneva University’s Institute of Global Health, told Health Policy Watch. “I am not sure that the priority is to give a third shot to entirely vaccinated populations when large parts of the world remain still very poorly covered. “I would suggest to ask regulatory authorities (e.g. EMA) to take a position rather than proposals coming from manufacturers which can always be prone to forms of conflicts of interest,” he added. “[Boosters] must be decided by bodies totally independent from producers.” At the same time, German’s Health Minister Jens Spahn, while visiting Geneva earlier this month, asserted that vaccine shortages elsewhere are not a good reason to hold off on boosters in high-income countries that already have large groups fully vaccinated. “I think we should be able to do both [administer boosters and vaccinate high-risk groups in other countries]. I want both to be possible for us to be able to provide a third vaccination, while also providing our first vaccination to everyone around the world…One shouldn’t come on the account of the other,” he said at an event at the Geneva Graduate Institute, adding that he expected vaccine surpluses, rather than shortages, by 2022. Re-evaluating the aims of vaccine policies It appears that policymakers have reached a crossroads where they could either attempt to prevent COVID infection, transmission, and mild disease altogether – or instead try to prevent severe hospitalisations and death in vulnerable groups, Eyal Leshem, Director of the Center for Travel Medicine and Tropical Diseases at Israel’s Sheba Medical Center, told Health Policy Watch. But as the coronavirus continues to mutate and vaccine doses remain scarce in poorer countries, preventing infection and transmission of SARS-CoV-2 in the whole population is bound to be a “challenging goal” for now, he added. “We are learning now that achieving population immunity is going to be a challenging goal in a world where the virus mutates and the vaccine is less effective in preventing infection and mild disease with new variants,” said Leshem. “We know this from other pathogens, where the purpose of the vaccine is to prevent severe hospitalisations and death [protective immunity] rather than to completely prevent infection [sterilizing immunity]. Those are two different approaches to public health protection now. “If you want to protect persons against severe disease and hospitalisations, then your target population are those that are at highest risk,” he said. First in a series on COVID-19 booster vaccines. See the second article, COVID Vaccine Boosters in Immuno-compromised People – Could They Also Help Curb Development of New Variants ? Image Credits: Flickr – New York National Guard. Share this:Click to share on Twitter (Opens in new window)Click to share on LinkedIn (Opens in new window)Click to share on Facebook (Opens in new window)Click to print (Opens in new window) Combat the infodemic in health information and support health policy reporting from the global South. Our growing network of journalists in Africa, Asia, Geneva and New York connect the dots between regional realities and the big global debates, with evidence-based, open access news and analysis. To make a personal or organisational contribution click here on PayPal.